Process of treating wood



' Jan. 4, 1927. 1,613,459

J. HIMMELSBACH PROCESS FOR 'I'REATING WOOD Filed uarchfl, 192e fN Figa?,

aan (EMMAQQAQ d-QL/ @1^ on 150g ATTO'RN EYS Patented Jan. 4, 1927.

UNITED STATES PATENT oFElcE.

JOSEPH HIMMELSBACH, OF FREIBURG, GERMANY, ASSIGNOR TO GEBR. HIMMELSBACH AKTIENGESELLSCHAFT, OF FREIBURG, GERMANY, A CORPORATION OF GERMANY.'

PROCESS OF TREATING WOOD.

Application led March 31, 1936, Serial No. 98,820, and in Germany November 3, 1925.

This invention is a novel process and apparatus for preliminarily treating wood for subsequent treatment with impregnating salts.

Heretofore, wood has been impregnated with salts, such as for example mercury chloride, sodium fluoride, zinc chloride, and the like, the wood being customarily placed in a saturating container containing the impregnating salts while the wood is in normal dried condition. By reason of the slowV penetration' of the li uor through the outerdry layer of the woo the period'of immersion in the vsaturation container has Abeen usually 8 to 10 days andthe impregnating salts depositing firmly on theeouter layer of the wood thus tends to prevent the impreguating solution from penetrating by diffusion. In order to make 4the wood more receptive for the impregnating salts or other medium, it has heretofore been proposed to steam the wood before the impregnating step, use being also made in addition to steam of acid and cresol containing vapors. The results of this treatment however have not proven satisfactory, for the following saturated portions will be, of course, dam'- aged or destroyed by the moisture in the air,

lby fungus growths, etc., more rapidly than the coated external layer of the wood, so that the interior of the pole will be destroyed by rot while the outer casing is still intact.

The novel process and apparatusof the present invention eliminates the necessity of the long period of -immersion of the wood in the impregnating salts. Moreover it'renders the. wood in such condition thatthe will penetrate morel impregnating salts deeply into the wood, and prevents cracking of the wood which results from uncovering the unsaturatedA portlons of the wood, after kyanizing,

The present lnvention consists in first Subjecting the wood, before saturation in the impregnating salts, to a rapid vaporization or steaming at a high temperature, in order to heat the wood to a high degree, and at the same time to meisten the exterior portion thereof which is usually drier than the interior. After this vaporization, which brings the wood to a uniformly moist and heated' state, artificial cracks in the wood are then formed by rapidly drying same vby means of hot air or the like, this being done more uniformly and completely than if the wood were Asubjected to the drying directly without vaporizing, as the drying would then not be uniform by reason of the influence of the inner moist core of the wood,- nor would the cracks be formed in as complete a manner as in the present process.

After the wood has been prepared according to these two steps, so that subsequent uncovering of unprotected parts of the wood can not take place, the wood is again sub, jected to a slmultaneous' vapor1z1ng process,

-as hot as possible, and a sprinkling or spraying process, the result of which is that on subsequent preservation the impregnating salts will/penetrate deeper, more uniformly, and more rapidly into the Wood. By simultaneously spraying with the condensate formed during the vaporization, to which acids, cresol, or hexanol and their homologues may be added, the wood is moistened through more completely and its absorptive capacity considerably increased. Moreover,

the repeated vaporization following, theA rapid drying and the thorough moistening through the spraying step, prevents the impregnating salt from depositing only on the outer layers of the wood as would be the case with dry or untreated wood. The impregnating solution penetrating by diffusion may thus penetrate without obstruction into the inner cells of the wood, thus effecting deeper and more uniform penetration.

ln the preserving step which followsthe above described preliminary treatment, the impregnating salts penetrate also into the artificially formed cracks, so that when or if these cracks are again exposedto the atmosphere no unprotected portions will be uncovered or exposed.

An exemplary embodiment of an apparatus for carrying out the process is 111ustrated diagrammatically in the accompanying drawing, in which:

Fig. 1 is a longitudinal section through the apparatus,

Fig. 2 is a horizontal section therethrough, and

. Fig. 3 is a transverse section on an enlarged scale.

The wood b to be treated is introduced preferably by means of trucks into the vaporizing and drying chamber a, whereupon the door c of the chamber is tightly closed. The vapor or steam is passed through the pipe Z in to thechamber a adjacent cach end.

The condensate from the steam forming in the chamber during this first step, is discharged vafter sufficient, duration of the vaporizing step. which duration depends on the amount of wood to be treated. The vapor or steam is then passed through the heating pipes e, which preferably extends longitudinally of the chamber a adjacent each lower corner thereof, and the temperature Within the chamber is raised quickly to about 150o C., and the wood bis thus subjected to rapid drying. Of eourse,other suitable means may be used for drying the Wood, for example, heating by air which is driven by a fan or the like over a heating resistance.

After the drying operation, the duration 'of which also depends on the amount of the Wood to be. treated, the vapor` or steam pipe al is again opened, whereby hot condensate collects at the bottom of chamber a, to which acids, cresol or hexanol and their homologues may be added. The hot liquid is passed by means of a pump f into the pipes g arranged in the chamber a above the Wood b, from which pipes g it exits through the openings 7L provided in said pipes. In order to effect a more uniform spraying it is preferable to allow the spraying liquid to pass upwardly from the pipes g, in order to provide a more effective spray which falls upon the Wood I).

After the above operation the wood may then be introduced directly into the saturating or impregnating receptacle before substantial cooling of the wood.

I claim:

1. The herein described Process for preliminarily treating wood for subsequent preservationby impregnation, consisting in treating the wood with steam; then subject- Ving the wood to rapid drying at a high temperature; then treating the. wood with steam and simultaneously spraying same with the condensate of the steam.

2. The herein described process-for preliminarily treating wood for subsequent preservation by impregnation, consisting in treating the Wood with steam; then subjecting the Wood to rapid drying at a high temperature; then treating'the Wood with steam, and simultaneously spraying same with the condensate of the steam to which has been added acids, cresols, or heXanol and their homologues.

3. The herein described process for preliminarily treating Wood for. subsequent preservation by impregnation, consisting in subjecting the Wood to vapors at a high temperature to moisten and heat same; then subjecting the wood to rapid drying in a temperature of approximately 150O C.; then again subjecting the Wood to said vapors,

subjecting the Wood to vapors at a high temperature to moisten and heat same; then subjecting the wood to rapid drying in a tenlperature approximately 150 C.; then again subjecting the Woo'd to said vapors, and simultaneously spraying same With the condensate of said vapors to which has been added acids, cresols, or hexanol and their homologues.

5. The herein described process for treating Wood for preservation consisting in subjecting the Wood to steam at a high temperature to moisten and heat same; then subjecting the Wood to rapid drying in a temperaturey of approximately 150 C.; then again subjecting the wood to steam, and simultaneously spraying same with the condensate ofthe steam; and nally immersing same in impregnating salt solution before substantial cooling of the Wood.

6. The herein described process for treat.- ing Wood for preservation, consisting in subject-ing the Wood to steam ata high temperature to meisten and heat same; then subjecting the wood to rapidv drying in a tempera- 'ture of approximately 150 C.; then again- JOSEPH HIMMELSBACH. 

